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<pre><span class="sourceLineNo">001</span>/*<a name="line.1"></a>
<span class="sourceLineNo">002</span> * Copyright (C) 2009 The Guava Authors<a name="line.2"></a>
<span class="sourceLineNo">003</span> *<a name="line.3"></a>
<span class="sourceLineNo">004</span> * Licensed under the Apache License, Version 2.0 (the "License");<a name="line.4"></a>
<span class="sourceLineNo">005</span> * you may not use this file except in compliance with the License.<a name="line.5"></a>
<span class="sourceLineNo">006</span> * You may obtain a copy of the License at<a name="line.6"></a>
<span class="sourceLineNo">007</span> *<a name="line.7"></a>
<span class="sourceLineNo">008</span> * http://www.apache.org/licenses/LICENSE-2.0<a name="line.8"></a>
<span class="sourceLineNo">009</span> *<a name="line.9"></a>
<span class="sourceLineNo">010</span> * Unless required by applicable law or agreed to in writing, software<a name="line.10"></a>
<span class="sourceLineNo">011</span> * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.11"></a>
<span class="sourceLineNo">012</span> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.12"></a>
<span class="sourceLineNo">013</span> * See the License for the specific language governing permissions and<a name="line.13"></a>
<span class="sourceLineNo">014</span> * limitations under the License.<a name="line.14"></a>
<span class="sourceLineNo">015</span> */<a name="line.15"></a>
<span class="sourceLineNo">016</span><a name="line.16"></a>
<span class="sourceLineNo">017</span>package com.google.common.collect;<a name="line.17"></a>
<span class="sourceLineNo">018</span><a name="line.18"></a>
<span class="sourceLineNo">019</span>import com.google.common.annotations.GwtCompatible;<a name="line.19"></a>
<span class="sourceLineNo">020</span>import com.google.common.primitives.Booleans;<a name="line.20"></a>
<span class="sourceLineNo">021</span>import com.google.common.primitives.Ints;<a name="line.21"></a>
<span class="sourceLineNo">022</span>import com.google.common.primitives.Longs;<a name="line.22"></a>
<span class="sourceLineNo">023</span><a name="line.23"></a>
<span class="sourceLineNo">024</span>import java.util.Comparator;<a name="line.24"></a>
<span class="sourceLineNo">025</span><a name="line.25"></a>
<span class="sourceLineNo">026</span>import javax.annotation.Nullable;<a name="line.26"></a>
<span class="sourceLineNo">027</span><a name="line.27"></a>
<span class="sourceLineNo">028</span>/**<a name="line.28"></a>
<span class="sourceLineNo">029</span> * A utility for performing a "lazy" chained comparison statement, which <a name="line.29"></a>
<span class="sourceLineNo">030</span> * performs comparisons only until it finds a nonzero result. For example:<a name="line.30"></a>
<span class="sourceLineNo">031</span> * &lt;pre&gt;   {@code<a name="line.31"></a>
<span class="sourceLineNo">032</span> *<a name="line.32"></a>
<span class="sourceLineNo">033</span> *   public int compareTo(Foo that) {<a name="line.33"></a>
<span class="sourceLineNo">034</span> *     return ComparisonChain.start()<a name="line.34"></a>
<span class="sourceLineNo">035</span> *         .compare(this.aString, that.aString)<a name="line.35"></a>
<span class="sourceLineNo">036</span> *         .compare(this.anInt, that.anInt)<a name="line.36"></a>
<span class="sourceLineNo">037</span> *         .compare(this.anEnum, that.anEnum, Ordering.natural().nullsLast())<a name="line.37"></a>
<span class="sourceLineNo">038</span> *         .result();<a name="line.38"></a>
<span class="sourceLineNo">039</span> *   }}&lt;/pre&gt;<a name="line.39"></a>
<span class="sourceLineNo">040</span> *<a name="line.40"></a>
<span class="sourceLineNo">041</span> * The value of this expression will have the same sign as the &lt;i&gt;first<a name="line.41"></a>
<span class="sourceLineNo">042</span> * nonzero&lt;/i&gt; comparison result in the chain, or will be zero if every<a name="line.42"></a>
<span class="sourceLineNo">043</span> * comparison result was zero.<a name="line.43"></a>
<span class="sourceLineNo">044</span> *<a name="line.44"></a>
<span class="sourceLineNo">045</span> * &lt;p&gt;Once any comparison returns a nonzero value, remaining comparisons are<a name="line.45"></a>
<span class="sourceLineNo">046</span> * "short-circuited".<a name="line.46"></a>
<span class="sourceLineNo">047</span> * <a name="line.47"></a>
<span class="sourceLineNo">048</span> * &lt;p&gt;See the Guava User Guide article on &lt;a href=<a name="line.48"></a>
<span class="sourceLineNo">049</span> * "http://code.google.com/p/guava-libraries/wiki/CommonObjectUtilitiesExplained#compare/compareTo"&gt;<a name="line.49"></a>
<span class="sourceLineNo">050</span> * {@code ComparisonChain}&lt;/a&gt;.<a name="line.50"></a>
<span class="sourceLineNo">051</span> *<a name="line.51"></a>
<span class="sourceLineNo">052</span> * @author Mark Davis<a name="line.52"></a>
<span class="sourceLineNo">053</span> * @author Kevin Bourrillion<a name="line.53"></a>
<span class="sourceLineNo">054</span> * @since 2.0<a name="line.54"></a>
<span class="sourceLineNo">055</span> */<a name="line.55"></a>
<span class="sourceLineNo">056</span>@GwtCompatible<a name="line.56"></a>
<span class="sourceLineNo">057</span>public abstract class ComparisonChain {<a name="line.57"></a>
<span class="sourceLineNo">058</span>  private ComparisonChain() {}<a name="line.58"></a>
<span class="sourceLineNo">059</span><a name="line.59"></a>
<span class="sourceLineNo">060</span>  /**<a name="line.60"></a>
<span class="sourceLineNo">061</span>   * Begins a new chained comparison statement. See example in the class<a name="line.61"></a>
<span class="sourceLineNo">062</span>   * documentation.<a name="line.62"></a>
<span class="sourceLineNo">063</span>   */<a name="line.63"></a>
<span class="sourceLineNo">064</span>  public static ComparisonChain start() {<a name="line.64"></a>
<span class="sourceLineNo">065</span>    return ACTIVE;<a name="line.65"></a>
<span class="sourceLineNo">066</span>  }<a name="line.66"></a>
<span class="sourceLineNo">067</span><a name="line.67"></a>
<span class="sourceLineNo">068</span>  private static final ComparisonChain ACTIVE = new ComparisonChain() {<a name="line.68"></a>
<span class="sourceLineNo">069</span>    @SuppressWarnings("unchecked")<a name="line.69"></a>
<span class="sourceLineNo">070</span>    @Override public ComparisonChain compare(<a name="line.70"></a>
<span class="sourceLineNo">071</span>        Comparable left, Comparable right) {<a name="line.71"></a>
<span class="sourceLineNo">072</span>      return classify(left.compareTo(right));<a name="line.72"></a>
<span class="sourceLineNo">073</span>    }<a name="line.73"></a>
<span class="sourceLineNo">074</span>    @Override public &lt;T&gt; ComparisonChain compare(<a name="line.74"></a>
<span class="sourceLineNo">075</span>        @Nullable T left, @Nullable T right, Comparator&lt;T&gt; comparator) {<a name="line.75"></a>
<span class="sourceLineNo">076</span>      return classify(comparator.compare(left, right));<a name="line.76"></a>
<span class="sourceLineNo">077</span>    }<a name="line.77"></a>
<span class="sourceLineNo">078</span>    @Override public ComparisonChain compare(int left, int right) {<a name="line.78"></a>
<span class="sourceLineNo">079</span>      return classify(Ints.compare(left, right));<a name="line.79"></a>
<span class="sourceLineNo">080</span>    }<a name="line.80"></a>
<span class="sourceLineNo">081</span>    @Override public ComparisonChain compare(long left, long right) {<a name="line.81"></a>
<span class="sourceLineNo">082</span>      return classify(Longs.compare(left, right));<a name="line.82"></a>
<span class="sourceLineNo">083</span>    }<a name="line.83"></a>
<span class="sourceLineNo">084</span>    @Override public ComparisonChain compare(float left, float right) {<a name="line.84"></a>
<span class="sourceLineNo">085</span>      return classify(Float.compare(left, right));<a name="line.85"></a>
<span class="sourceLineNo">086</span>    }<a name="line.86"></a>
<span class="sourceLineNo">087</span>    @Override public ComparisonChain compare(double left, double right) {<a name="line.87"></a>
<span class="sourceLineNo">088</span>      return classify(Double.compare(left, right));<a name="line.88"></a>
<span class="sourceLineNo">089</span>    }<a name="line.89"></a>
<span class="sourceLineNo">090</span>    @Override public ComparisonChain compareTrueFirst(boolean left, boolean right) {<a name="line.90"></a>
<span class="sourceLineNo">091</span>      return classify(Booleans.compare(right, left)); // reversed<a name="line.91"></a>
<span class="sourceLineNo">092</span>    }<a name="line.92"></a>
<span class="sourceLineNo">093</span>    @Override public ComparisonChain compareFalseFirst(boolean left, boolean right) {<a name="line.93"></a>
<span class="sourceLineNo">094</span>      return classify(Booleans.compare(left, right));<a name="line.94"></a>
<span class="sourceLineNo">095</span>    }<a name="line.95"></a>
<span class="sourceLineNo">096</span>    ComparisonChain classify(int result) {<a name="line.96"></a>
<span class="sourceLineNo">097</span>      return (result &lt; 0) ? LESS : (result &gt; 0) ? GREATER : ACTIVE;<a name="line.97"></a>
<span class="sourceLineNo">098</span>    }<a name="line.98"></a>
<span class="sourceLineNo">099</span>    @Override public int result() {<a name="line.99"></a>
<span class="sourceLineNo">100</span>      return 0;<a name="line.100"></a>
<span class="sourceLineNo">101</span>    }<a name="line.101"></a>
<span class="sourceLineNo">102</span>  };<a name="line.102"></a>
<span class="sourceLineNo">103</span><a name="line.103"></a>
<span class="sourceLineNo">104</span>  private static final ComparisonChain LESS = new InactiveComparisonChain(-1);<a name="line.104"></a>
<span class="sourceLineNo">105</span><a name="line.105"></a>
<span class="sourceLineNo">106</span>  private static final ComparisonChain GREATER = new InactiveComparisonChain(1);<a name="line.106"></a>
<span class="sourceLineNo">107</span><a name="line.107"></a>
<span class="sourceLineNo">108</span>  private static final class InactiveComparisonChain extends ComparisonChain {<a name="line.108"></a>
<span class="sourceLineNo">109</span>    final int result;<a name="line.109"></a>
<span class="sourceLineNo">110</span><a name="line.110"></a>
<span class="sourceLineNo">111</span>    InactiveComparisonChain(int result) {<a name="line.111"></a>
<span class="sourceLineNo">112</span>      this.result = result;<a name="line.112"></a>
<span class="sourceLineNo">113</span>    }<a name="line.113"></a>
<span class="sourceLineNo">114</span>    @Override public ComparisonChain compare(<a name="line.114"></a>
<span class="sourceLineNo">115</span>        @Nullable Comparable left, @Nullable Comparable right) {<a name="line.115"></a>
<span class="sourceLineNo">116</span>      return this;<a name="line.116"></a>
<span class="sourceLineNo">117</span>    }<a name="line.117"></a>
<span class="sourceLineNo">118</span>    @Override public &lt;T&gt; ComparisonChain compare(@Nullable T left,<a name="line.118"></a>
<span class="sourceLineNo">119</span>        @Nullable T right, @Nullable Comparator&lt;T&gt; comparator) {<a name="line.119"></a>
<span class="sourceLineNo">120</span>      return this;<a name="line.120"></a>
<span class="sourceLineNo">121</span>    }<a name="line.121"></a>
<span class="sourceLineNo">122</span>    @Override public ComparisonChain compare(int left, int right) {<a name="line.122"></a>
<span class="sourceLineNo">123</span>      return this;<a name="line.123"></a>
<span class="sourceLineNo">124</span>    }<a name="line.124"></a>
<span class="sourceLineNo">125</span>    @Override public ComparisonChain compare(long left, long right) {<a name="line.125"></a>
<span class="sourceLineNo">126</span>      return this;<a name="line.126"></a>
<span class="sourceLineNo">127</span>    }<a name="line.127"></a>
<span class="sourceLineNo">128</span>    @Override public ComparisonChain compare(float left, float right) {<a name="line.128"></a>
<span class="sourceLineNo">129</span>      return this;<a name="line.129"></a>
<span class="sourceLineNo">130</span>    }<a name="line.130"></a>
<span class="sourceLineNo">131</span>    @Override public ComparisonChain compare(double left, double right) {<a name="line.131"></a>
<span class="sourceLineNo">132</span>      return this;<a name="line.132"></a>
<span class="sourceLineNo">133</span>    }<a name="line.133"></a>
<span class="sourceLineNo">134</span>    @Override public ComparisonChain compareTrueFirst(boolean left, boolean right) {<a name="line.134"></a>
<span class="sourceLineNo">135</span>      return this;<a name="line.135"></a>
<span class="sourceLineNo">136</span>    }<a name="line.136"></a>
<span class="sourceLineNo">137</span>    @Override public ComparisonChain compareFalseFirst(boolean left, boolean right) {<a name="line.137"></a>
<span class="sourceLineNo">138</span>      return this;<a name="line.138"></a>
<span class="sourceLineNo">139</span>    }<a name="line.139"></a>
<span class="sourceLineNo">140</span>    @Override public int result() {<a name="line.140"></a>
<span class="sourceLineNo">141</span>      return result;<a name="line.141"></a>
<span class="sourceLineNo">142</span>    }<a name="line.142"></a>
<span class="sourceLineNo">143</span>  }<a name="line.143"></a>
<span class="sourceLineNo">144</span><a name="line.144"></a>
<span class="sourceLineNo">145</span>  /**<a name="line.145"></a>
<span class="sourceLineNo">146</span>   * Compares two comparable objects as specified by {@link<a name="line.146"></a>
<span class="sourceLineNo">147</span>   * Comparable#compareTo}, &lt;i&gt;if&lt;/i&gt; the result of this comparison chain<a name="line.147"></a>
<span class="sourceLineNo">148</span>   * has not already been determined.<a name="line.148"></a>
<span class="sourceLineNo">149</span>   */<a name="line.149"></a>
<span class="sourceLineNo">150</span>  public abstract ComparisonChain compare(<a name="line.150"></a>
<span class="sourceLineNo">151</span>      Comparable&lt;?&gt; left, Comparable&lt;?&gt; right);<a name="line.151"></a>
<span class="sourceLineNo">152</span><a name="line.152"></a>
<span class="sourceLineNo">153</span>  /**<a name="line.153"></a>
<span class="sourceLineNo">154</span>   * Compares two objects using a comparator, &lt;i&gt;if&lt;/i&gt; the result of this<a name="line.154"></a>
<span class="sourceLineNo">155</span>   * comparison chain has not already been determined.<a name="line.155"></a>
<span class="sourceLineNo">156</span>   */<a name="line.156"></a>
<span class="sourceLineNo">157</span>  public abstract &lt;T&gt; ComparisonChain compare(<a name="line.157"></a>
<span class="sourceLineNo">158</span>      @Nullable T left, @Nullable T right, Comparator&lt;T&gt; comparator);<a name="line.158"></a>
<span class="sourceLineNo">159</span><a name="line.159"></a>
<span class="sourceLineNo">160</span>  /**<a name="line.160"></a>
<span class="sourceLineNo">161</span>   * Compares two {@code int} values as specified by {@link Ints#compare},<a name="line.161"></a>
<span class="sourceLineNo">162</span>   * &lt;i&gt;if&lt;/i&gt; the result of this comparison chain has not already been<a name="line.162"></a>
<span class="sourceLineNo">163</span>   * determined.<a name="line.163"></a>
<span class="sourceLineNo">164</span>   */<a name="line.164"></a>
<span class="sourceLineNo">165</span>  public abstract ComparisonChain compare(int left, int right);<a name="line.165"></a>
<span class="sourceLineNo">166</span><a name="line.166"></a>
<span class="sourceLineNo">167</span>  /**<a name="line.167"></a>
<span class="sourceLineNo">168</span>   * Compares two {@code long} values as specified by {@link Longs#compare},<a name="line.168"></a>
<span class="sourceLineNo">169</span>   * &lt;i&gt;if&lt;/i&gt; the result of this comparison chain has not already been<a name="line.169"></a>
<span class="sourceLineNo">170</span>   * determined.<a name="line.170"></a>
<span class="sourceLineNo">171</span>   */<a name="line.171"></a>
<span class="sourceLineNo">172</span>  public abstract ComparisonChain compare(long left, long right);<a name="line.172"></a>
<span class="sourceLineNo">173</span><a name="line.173"></a>
<span class="sourceLineNo">174</span>  /**<a name="line.174"></a>
<span class="sourceLineNo">175</span>   * Compares two {@code float} values as specified by {@link<a name="line.175"></a>
<span class="sourceLineNo">176</span>   * Float#compare}, &lt;i&gt;if&lt;/i&gt; the result of this comparison chain has not<a name="line.176"></a>
<span class="sourceLineNo">177</span>   * already been determined.<a name="line.177"></a>
<span class="sourceLineNo">178</span>   */<a name="line.178"></a>
<span class="sourceLineNo">179</span>  public abstract ComparisonChain compare(float left, float right);<a name="line.179"></a>
<span class="sourceLineNo">180</span><a name="line.180"></a>
<span class="sourceLineNo">181</span>  /**<a name="line.181"></a>
<span class="sourceLineNo">182</span>   * Compares two {@code double} values as specified by {@link<a name="line.182"></a>
<span class="sourceLineNo">183</span>   * Double#compare}, &lt;i&gt;if&lt;/i&gt; the result of this comparison chain has not<a name="line.183"></a>
<span class="sourceLineNo">184</span>   * already been determined.<a name="line.184"></a>
<span class="sourceLineNo">185</span>   */<a name="line.185"></a>
<span class="sourceLineNo">186</span>  public abstract ComparisonChain compare(double left, double right);<a name="line.186"></a>
<span class="sourceLineNo">187</span><a name="line.187"></a>
<span class="sourceLineNo">188</span>  /**<a name="line.188"></a>
<span class="sourceLineNo">189</span>   * Compares two {@code boolean} values, considering {@code true} to be less<a name="line.189"></a>
<span class="sourceLineNo">190</span>   * than {@code false}, &lt;i&gt;if&lt;/i&gt; the result of this comparison chain has not<a name="line.190"></a>
<span class="sourceLineNo">191</span>   * already been determined.<a name="line.191"></a>
<span class="sourceLineNo">192</span>   *<a name="line.192"></a>
<span class="sourceLineNo">193</span>   * @since 12.0<a name="line.193"></a>
<span class="sourceLineNo">194</span>   */<a name="line.194"></a>
<span class="sourceLineNo">195</span>  public abstract ComparisonChain compareTrueFirst(boolean left, boolean right);<a name="line.195"></a>
<span class="sourceLineNo">196</span><a name="line.196"></a>
<span class="sourceLineNo">197</span>  /**<a name="line.197"></a>
<span class="sourceLineNo">198</span>   * Compares two {@code boolean} values, considering {@code false} to be less<a name="line.198"></a>
<span class="sourceLineNo">199</span>   * than {@code true}, &lt;i&gt;if&lt;/i&gt; the result of this comparison chain has not<a name="line.199"></a>
<span class="sourceLineNo">200</span>   * already been determined.<a name="line.200"></a>
<span class="sourceLineNo">201</span>   *<a name="line.201"></a>
<span class="sourceLineNo">202</span>   * @since 12.0 (present as {@code compare} since 2.0)<a name="line.202"></a>
<span class="sourceLineNo">203</span>   */<a name="line.203"></a>
<span class="sourceLineNo">204</span>  public abstract ComparisonChain compareFalseFirst(boolean left, boolean right);<a name="line.204"></a>
<span class="sourceLineNo">205</span><a name="line.205"></a>
<span class="sourceLineNo">206</span>  /**<a name="line.206"></a>
<span class="sourceLineNo">207</span>   * Old name of {@link #compareFalseFirst}.<a name="line.207"></a>
<span class="sourceLineNo">208</span>   *<a name="line.208"></a>
<span class="sourceLineNo">209</span>   * @deprecated Use {@link #compareFalseFirst}; or, if the parameters passed<a name="line.209"></a>
<span class="sourceLineNo">210</span>   *     are being either negated or reversed, undo the negation or reversal and<a name="line.210"></a>
<span class="sourceLineNo">211</span>   *     use {@link #compareTrueFirst}. &lt;b&gt;This method is scheduled for deletion<a name="line.211"></a>
<span class="sourceLineNo">212</span>   *     in September 2013.&lt;/b&gt;<a name="line.212"></a>
<span class="sourceLineNo">213</span>   */<a name="line.213"></a>
<span class="sourceLineNo">214</span>  @Deprecated<a name="line.214"></a>
<span class="sourceLineNo">215</span>  public final ComparisonChain compare(boolean left, boolean right) {<a name="line.215"></a>
<span class="sourceLineNo">216</span>    return compareFalseFirst(left, right);<a name="line.216"></a>
<span class="sourceLineNo">217</span>  }<a name="line.217"></a>
<span class="sourceLineNo">218</span><a name="line.218"></a>
<span class="sourceLineNo">219</span>  /**<a name="line.219"></a>
<span class="sourceLineNo">220</span>   * Ends this comparison chain and returns its result: a value having the<a name="line.220"></a>
<span class="sourceLineNo">221</span>   * same sign as the first nonzero comparison result in the chain, or zero if<a name="line.221"></a>
<span class="sourceLineNo">222</span>   * every result was zero.<a name="line.222"></a>
<span class="sourceLineNo">223</span>   */<a name="line.223"></a>
<span class="sourceLineNo">224</span>  public abstract int result();<a name="line.224"></a>
<span class="sourceLineNo">225</span>}<a name="line.225"></a>




























































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